Ceramic tile may be either glazed or unglazed. A glaze is generally a glass coating, sometimes with added color, that is applied to the surface of a ceramic tile. Glazed tiles have surfaces that offer advantages such as resistance to wear, moisture, and stains. The strength and wear resistance of a glaze is generally determined by its hardness. That is, the harder the glaze, the better it will resist pressure and abrasion.
In addition, the wear resistance performance of traditional glazes is dependent in part on the color of the surface, where lighter colored glazes generally perform better than darker ones. Consequently, product design for high wear resistant products has been limited to light colors. Other alternative glaze technologies have been developed to provide improved wear resistance. These technologies, however, increase production costs or limit the range of appearance that can be achieved in the final tile products.
For example, many of these alternative technologies are based on glass-ceramic coatings or glazes. Frequently, the refractive indices of the resulting glass-ceramic coatings are high, resulting in high opacity, which limits the range of visual characteristics that can be achieved in the final tile product. In addition, some of these systems have coefficients of thermal expansion that are lower than those observed for ceramic tiles. This mismatch between the coating and the tile substrate can result in deformation of the tile or coverage defects such as crazing or crawling.
Accordingly, there is a need for improved wear resistant coatings or glazes for ceramic tiles. It is to the provision of such coatings, and the associated wear resistant tiles that the various embodiments of the present invention are directed.